BookMooch now has 40,000 members around the world, according to Mr. Buckman, and people are joining at a rate of 300 a day. Participants create an inventory (the books they want to give away) and a wish list (the books they want to own).

The company that brought soap operas to radio, then television, Procter & Gamble, is trying the same strategy online with â€œCrescent Heights,â€ a new show intended to reach young viewers where they watch the most â€” their PCs and cellphones.

A report by JupiterResearch looked at 277 online advertisers and found that 42 percent used some target marketing, but only 23 percent used a combination of data â€” like geographic and demographic information â€” to send ads to consumers.

But as he and Mr. Yonda began fleshing out the character of Darth Vaderâ€™s hapless younger brother, Chad, a shift manager in the Empire Market who canâ€™t land a date despite his Jedi powers, Mr. Sloan said, â€œI knew we had something special.â€

â€œWhen confronted with the opportunity to buy something, the buyerâ€™s attitude is always â€˜Why do I need this,â€™â€ Ms. Gardner says. â€œThe more you talk, the more likely you are to say something that causes your buyer to say: â€˜I donâ€™t need that